1. Field of the Invention
The present invention relates to diene rubber compositions usable for the manufacture of tires or semi-finished products for tires, in particular of treads for these tires, and to the reinforcing inorganic fillers capable of reinforcing such rubber compositions.
2. Description of Related Art
So as to reduce fuel consumption and the pollution emitted by motor vehicles, major attempts have been made by tire designers to obtain tires having all of the following: very low rolling resistance, improved adhesion both on dry ground and on wet or snow-covered ground, and good wear resistance.
Numerous solutions have in particular been proposed in the past for lowering the rolling resistance and improving the grip of tires, but these generally result in very significant decline of the wear resistance.
In particular, it is well known that although the incorporation of conventional white fillers such as, for example, conventional silicas or aluminas, chalk, talc, natural aluminosilicates such as bentonite or kaolin, in rubber compositions used for the manufacture of tires and in particular of treads, does result in a reduction in the rolling resistance and an improvement in adhesion to wet, snow-covered or icy ground, it also results in an unacceptable decline in the wear resistance, linked to the fact that these conventional white fillers do not have a sufficient reinforcement ability with respect to such rubber compositions.
For this reason, these white fillers are generally referred to as non-reinforcing fillers, also referred to as inert fillers.
One effective solution to this problem of insufficient wear resistance has been found due to the recent development, in the last ten years, of new rubber compositions comprising truly reinforcing inorganic fillers, in particular highly dispersible silicas referred to as “HDS” (for “Highly Dispersible Silica”), which have proved capable of replacing conventional carbon blacks for tires (see for example patents or patent applications EP 501 227, EP 692 492, EP 692 493, EP 735 088, EP 810 258, WO99/02590, WO99/02602, WO99/28376, WO 01/96442, WO 02/30939, WO 02/31041 and WO 02/083782).
The compositions based on HDS silica however have the known drawback of having very substantially slower vulcanization kinetics, as a general rule slower by a factor of two to three, compared with conventional compositions filled with carbon black. It is known that the longer curing times which result adversely affect the industrial processing of tires or treads for tires based on such compositions.